The present invention relates to vertical height adjustment mechanisms for chairs.
Many existing chairs have vertical height adjustment mechanisms that include vertically extendable gas springs. Typically, the gas spring includes a vertically operated release button that extends above the gas spring into an area under a chair seat, and the seat includes an actuator that can be manipulated by a seated user to depress the release button to unlock the gas spring. Upon release, the gas spring biases the seat upwardly. Alternatively, the seated user can, after unlocking the release button, press downwardly on the chair to overcome the bias of the gas spring to force the seat downwardly. However, the upright vertical position of the release button and its vertical operation cause these known height adjustment arrangements to require significant vertical space above the gas spring and under the seat. This is inconsistent with many modem chair designs, which call for a thin seat construction having sleek lines. Further, the structure necessary to provide the vertical space required for the vertically operated release button results in a heavier chair with more expensive and massive parts. Another problem with known vertical height adjustment mechanisms is that many are relatively complex and intricate, such that they are subject to mis-assembly, quality problems, and/or field failure.
Accordingly, a vertical height adjustment mechanism is desired that is reliable, is relatively non-complex, solves the aforementioned problems, and has the aforementioned advantages.